Fatty acid modified alkyd resin compositions, and the processes for their preparation, are well known in the art. Generally, these compositions are obtained by the reaction of polybasic acids, polyhydric alcohols, and fatty acids. The conventional oil modified alkyd resins are utilized in the painting industry as coatings such as lacquers, enamels, coating compounds, and the like. To utilize these alkyd resins as coatings generally requires the addition of a solvent, i.e., turpentine oil, toluene, xylene, or the like, in order to achieve a viscosity suitable for application.
Fatty acid modified alkyd coatings with a high solids content are particularly useful because, by increasing the molecular weight of the resin, improved physical characteristics and a diminished drying time are achieved. However, an increase in the molecular weight results in an increase in the solvents required, which solvents are environmental pollutants and are useless once the coating film forms. The solvent requirement may be decreased by increasing the alkyd resin oil length, i.e., the weight percentage of formed triglyceride in the resin. However, increasing the oil length produces a coating in which the drying time is increased also.
U.S. Pat. No. 5,039,740 to Anderson et al. discloses a high solids fatty acid modified alkyd coating composition in which the solvent requirement is diminished yet the oil length of the alkyd does not exceed 35%. Specifically, Anderson et al. discloses a high solids fatty acid modified alkyd resin in which a portion of the solvent is replaced by vinyl unsaturated monomers or oligomers that are capable of free radical initiated addition polymerization. The resulting resins exhibit good physical and cure properties. However, the resins have been observed to exhibit poor adhesion to substrates.
The present invention is directed to fatty acid modified alkyd resins and high solids fatty acid modified alkyd resins which exhibit improved substrate adhesion.